Mortar rounds were said to have been fired into orchards in Kafr Souseh in an apparent offensive against rebels.

Independent confirmation is impossible, as journalists' freedom of movement is heavily restricted.

Syria has been convulsed by internal conflict since protests against President Assad began early last year. The protests turned into an armed rebellion and thousands of people have been killed.

'Clear consequences'

Western nations are pressing the UN to threaten Damascus with sanctions as it considers renewing the mandate for its observer mission in Syria which expires on 20 July.

They want a 10-day ultimatum to be part of a Security Council resolution on the future of the UN's observer mission in the country. A new resolution must be passed before the mission's mandate ends on Friday next week.

The mission had a 90-day remit to monitor a truce, but fighting has continued largely unabated.

The truce formed part of a six-point peace plan brokered by UN-Arab League envoy Kofi Annan, who has called for "clear consequences" for the Syrian government and rebels if the ceasefire is not observed.

Russia has suggested a 90-day extension. But Western states say a simple rollover of the mission is not enough.

A draft resolution has been circulated threatening Damascus with sanctions within 10 days, if it fails to stop using heavy weapons and pull back its troops from towns and cities.